Capacity of Outdoor VLC Links Using a Visible LASER Beam

Visible light communications (VLC) technology has gained more interest recently. It is mostly investigated for indoor applications because of the dual use of light emitting diodes (LEDs) and its cost-effectiveness. However, few outdoor VLC applications are identified. VLC is, for example, proposed as a solution to link buildings situated at a reasonable distance in environments such as headquarters and school campuses. It is also proposed as a solution for the access network. These outdoor VLC applications are enabled by the utilization, in VLC, of light amplification by stimulated emission of radiation (LASER) diodes (LDs). One of the reasons for this is their lighting range which is higher than that of LEDs, usually used in VLC. The use of LASER beams in outdoor VLC technology over a medium distance requires the knowledge of both the channel response and the environment. In this paper, we analyze the outdoor VLC link that uses LDs as transmitting antennas with a small angle divergence. Few link evaluation metrics including the signal-to-noise ratio (SNR), the channel capacity and the outage probability are presented based on the channel direct current (DC) gain proposed in the literature. Results show that the SNR of such systems is proportional to Pt/N0, they also show that the channel capacity increases with Pt/N0 depending on the haze and fog attenuation factor, ß. Finally, the outage probability increases towards 10° as the data rate increases for a fixed Pt/N0, and for a fixed value of the outage probability, the data rate increases with Pt/No.